Communication in large-scale distributed systems is mostly based on the publish/subscribe (pub/sub) paradigm, where content creators and interested recipients are decoupled in space, time, and synchronization. With the rise of social applications and the wide distribution of mobile devices highly dynamic scenarios for pub/sub systems become increasingly interesting, requiring the system to be adaptive in order to react to environmental conditions. This paper identifies promising adaptations in pub/sub systems and proposes the novel concept of transitions between multiple pub/sub mechanisms. Transitions enable a pub/sub system to react to a wide range of conditions by switching to the mechanism that fits the current environmental conditions best. This concept leads to a range of interesting research questions, which are presented and addressed in this paper.